Time Zone Converter

Every place on Earth sets its clocks as an offset from UTC, Coordinated Universal Time. New York in summer is UTC−4, so its clocks read 4 hours behind UTC. The tool first turns your time into UTC, then adds the offset of each city you picked:

The offsets come from the IANA time zone database, the rule book built into your browser and phone. It records when each country moves its clocks, so the tool uses the offset in force on the date you choose, not a fixed number. Some offsets are not whole hours. India is UTC+5:30 all year, and Kathmandu is UTC+5:45.

The Working card shows both steps for your own cities and checks the result by converting it back. The planner runs the same sum for every hour of your day.

Ana's team call from New York

Ana wants a call at 9:00 am New York time on Friday, October 23, 2026. New York is on daylight time, UTC−4. That is 2:00 pm in London, 6:30 pm in India and 10:00 pm in Tokyo. London is mid-afternoon, India is in the evening and Tokyo is at night, so the planner is the place to look for a better slot.

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The week the gap shrinks

The UK puts its clocks back on October 25, 2026, but the US waits until November 1. So on Monday, October 26, 9:00 am in New York is 1:00 pm in London, not the usual 2:00 pm. A week later, on November 2, it is 2:00 pm again. The same thing happens for three weeks in March, when the US moves its clocks forward first.

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A 3:00 pm London webinar

A webinar is set for 3:00 pm London time on October 23, 2026. That is 10:00 am in New York, 6:00 pm in Dubai and 10:00 pm in Singapore. In Sydney it is 1:00 am on Saturday, the next day, because Sydney is UTC+11 on its summer time.

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The big time is the clock reading in the To city at the moment you chose. The line under it gives the date there and both offsets. If the date says next day or previous day, the two cities are on different calendar days.

The first tile says how far ahead or behind the other city's clock is on that date. That gap is not fixed. In the US, clocks go forward on the second Sunday in March and back on the first Sunday in November, under 15 U.S.C. 260a. The UK and the EU change on the last Sunday in March and the last Sunday in October, at 01:00 UTC, under Directive 2000/84/EC. Australia's southeast and New Zealand do the opposite, with summer time from about October to April. India, China, Japan and most of Africa do not change at all.

The planner shades 9 am to 5 pm in teal and 10 pm to 7 am in gray in each city. These are common office hours, not a rule; shift workers and many countries keep other hours. The Next clock changes card lists the next date each city changes, so you can see whether a meeting set weeks ahead will move.

• Writing EST in summer. New York is on EST, UTC−5, only in winter. From March to November it is EDT, UTC−4. An invite that says "10:00 EST" in July is an hour off if someone takes it literally. Name the city, or write ET.
• Treating GMT as London time all year. London is on GMT in winter and BST, UTC+1, in summer.
• Assuming the gap never changes. New York to London is usually 5 hours, but it is 4 hours for about three weeks in March and one week from late October.
• Missing the date line. A Friday afternoon in London is already Saturday morning in Sydney and Auckland. Check the date tile, not just the time.
• Using a time that does not exist. On March 8, 2026, New York clocks jump from 2:00 am to 3:00 am, so 2:30 am never happens. The tool reads it as 3:30 am and warns you.